A downhole throttling device

Abstract

The present application relates to a kind of downhole throttling devices, comprising: the outer cylinder is arranged in downhole pipe body, the outer cylinder has the first passage of fluid flow, and the sealing mechanism can be inserted into the outer cylinder from the upper end of the outer cylinder and is connected in the throttling nozzle of the lower end of the outer cylinder.Therein, the sealing mechanism has the first state of sealing the outer cylinder and the second state of making the outer cylinder keep open.When the sealing mechanism is in the first state, the outer cylinder can be moved along the axial direction of downhole pipe body under the action of high-pressure fluid from the upper end;When the sealing mechanism is in the second state, fluid from the outer cylinder can flow out through the throttling nozzle.The downhole throttling device of the present application can be effectively applied to the gas well with larger inclination, and can also be smoothly lowered to the horizontal section of gas well.

Description

Technical Field

[0001] This invention relates to a downhole throttling device. Background Technology

[0002] In natural gas well production, downhole pressure reducers are typically used to reduce pressure within the wellbore. These downhole pressure reducers transfer the pressure reduction process from the surface to the wellbore, utilizing formation temperature to heat the low-temperature natural gas. This allows the temperature after pressure reduction to essentially return to the formation temperature at the wellbore depth, reducing the risk of ice blockage. This, in turn, helps extend the well's production life.

[0003] In existing technologies, downhole chokes are typically lowered to a predetermined depth using equipment such as steel wires or cables to implement downhole chokes. Because this method relies solely on the weight of the tool string itself for descent, the insertion angle is limited, making it unsuitable for gas wells with steep inclinations. Furthermore, this method makes it difficult to lower the downhole choke to the horizontal section of the gas well. These problems severely restrict the use of downhole chokes. Summary of the Invention

[0004] To address the technical problems described above, this invention aims to provide a downhole throttling device. This downhole throttling device can be effectively applied to gas wells with large deflections, and can also be smoothly deployed into the horizontal section of the gas well.

[0005] According to the present invention, a downhole throttling device is provided, comprising an outer cylinder disposed within a downhole casing, the outer cylinder having a first fluid flow channel, a sealing mechanism capable of being inserted into the outer cylinder from the top of the outer cylinder, and a throttling nozzle connected to a first end of the outer cylinder.

[0006] The sealing mechanism has a first state of sealing the outer cylinder and a second state of keeping the outer cylinder unobstructed. When the sealing mechanism is in the first state, the outer cylinder can move axially along the downhole casing under the action of high-pressure fluid from the upper end; when the sealing mechanism is in the second state, fluid from the upper end of the outer cylinder can flow out through the throttle nozzle.

[0007] In a preferred embodiment, the sealing mechanism includes a ball seat disposed within the outer cylinder and a sealing ball capable of setting the ball seat, the sealing ball being made of a material capable of dissolving under the flushing of downhole fluids.

[0008] In a preferred embodiment, the system further includes a positioning cylinder connected to the downhole casing, the outer cylinder being able to extend into and move within the positioning cylinder. A fixing member is provided on the outer wall of the outer cylinder, and a connecting portion is provided on the inner wall of the positioning cylinder. The fixing member has a fixed state capable of connecting with the connecting portion and a free state capable of disengaging from the connecting portion.

[0009] In a preferred embodiment, the connecting part is configured as a groove disposed within the positioning cylinder, and the fixing member is configured as a spring piece connected to the outer wall of the outer cylinder. The spring piece can open or retract radially along the positioning cylinder, thereby extending into or exiting the groove.

[0010] In a preferred embodiment, the ball seat is connected to the outer cylinder via a first shear pin, allowing the ball seat to move relative to the outer cylinder. A pusher is also provided on the ball seat, positioned on the side of the spring piece away from the outer cylinder, so that when the pusher moves upward relative to the spring piece, it can push the spring piece to retract.

[0011] In a preferred embodiment, a retrieval tube is also included, which is connected to the upper end of the ball seat.

[0012] In a preferred embodiment, a sealing rubber sleeve is further provided on the outer wall of the throttle nozzle, and the lower end of the pusher abuts against the sealing rubber sleeve, so that the pusher can push the sealing rubber sleeve to expand when it moves downward relative to the spring.

[0013] In a preferred embodiment, a ratchet ring is provided on the outer wall of the outer cylinder, and a one-way tooth is provided on the push cylinder that can engage with the ratchet ring.

[0014] In a preferred embodiment, the ratchet ring is connected to the outer cylinder by a second shear pin, the second shear pin being configured to have a shearing force greater than that of the first shear pin.

[0015] In a preferred embodiment, a sand guard is also provided at the lower end of the throttle nozzle. Attached Figure Description

[0016] The invention will now be described with reference to the accompanying drawings.

[0017] Figure 1 A schematic diagram of a downhole throttling device according to an embodiment of the present invention is shown.

[0018] Figure 2 for Figure 1 A partially enlarged schematic diagram of the downhole throttling device shown.

[0019] In this application, all drawings are schematic and are used only to illustrate the principles of the invention, and are not drawn to scale. Detailed Implementation

[0020] The invention will now be described with reference to the accompanying drawings. In this document, the terms "upper end" and "upper side" refer to the end or side pointing towards the wellhead; the terms "lower end" and "lower side" refer to the end or side away from the wellhead.

[0021] Figure 1 A downhole throttling device 100 according to an embodiment of the present invention is shown. For example... Figure 1 As shown, the downhole throttling device 100 includes an outer cylinder 10, which is arranged inside a downhole casing (not shown) and is capable of moving axially along the downhole casing under external force to reach a specified downhole depth. A first fluid flow channel 12 is defined within the outer cylinder 10.

[0022] Meanwhile, the downhole throttling device 100 of the present invention also includes a throttling nozzle 20 disposed at the lower end of the outer cylinder 10 and communicating with the first channel 12, and a sealing mechanism 30 disposed at the upper end of the outer cylinder 10 and capable of sealing the first channel 12.

[0023] like Figure 1 As shown, the sealing mechanism 30 includes a ball seat 32 fixedly connected inside the outer cylinder 10. The ball seat 32 is inserted into the first channel 12 from the upper end of the outer cylinder 10, thereby sealing the first channel 12. A second fluid flow channel 34 is defined within the ball seat 32, and the second channel 34 is provided with a sealing ball 36 capable of setting the ball seat 32.

[0024] In this invention, the sealing ball 36 is made of a material that can dissolve under the flushing action of downhole fluids. The material can be, for example, a magnesium-aluminum alloy. This material can dissolve under the flushing action of acidic or alkaline liquids downhole. When the sealing ball 36 is not dissolved, it seals the second channel 34, thereby sealing the first channel 12, at which point the sealing mechanism 30 is in a first state. When the sealing ball 36 dissolves, the second channel 34 is opened. At this time, the sealing mechanism 30 is in a second state, and downhole fluid can pass through the second channel 34 through the outer cylinder 10, thereby reaching the throttle nozzle 20.

[0025] It is easy to understand that when the second channel 34 is sealed, the high-pressure fluid downhole cannot pass through the second channel 34. Therefore, the high-pressure fluid flowing from the upper end of the outer cylinder 10 to the lower end of the outer cylinder 10 will exert a force on the outer cylinder 10, thereby pushing the outer cylinder 10 downward. When the sealing ball 36 dissolves and the second channel 34 is in a connected state, the downhole fluid can smoothly pass through the outer cylinder 10 to reach the throttle nozzle 20, achieving the throttling effect of the downhole throttling device 100.

[0026] This setup allows the downhole choke device 100 to be moved within the downhole pipeline by the pressure of the downhole fluid, thereby reaching the designated location. This solves the problem in existing wireline deployment technologies where the downhole choke device 100 has limited deployment angle and is difficult to deploy to inclined or horizontal sections of gas wells.

[0027] like Figure 1 As shown, the downhole throttling device 100 further includes a positioning cylinder 50 connected to the downhole pipe body. The outer cylinder 10 can extend into the positioning cylinder 50 and move within it. A fixing member 15 is provided on the outer wall of the outer cylinder 10, and a connecting part 55 is provided on the inner wall of the positioning cylinder 50. The fixing member 15 has a fixed state that can be connected to the connecting part 55 and a free state that can be detached from the connecting part.

[0028] Specifically, the connecting part 55 is configured as a groove on the inner wall of the positioning cylinder 50, and the fixing member 15 is configured as a spring piece 151 connected to the outer wall of the outer cylinder. The spring piece 151 has a certain elasticity, allowing it to open radially along the positioning cylinder, thereby extending into the groove and forming a fixed connection with the positioning cylinder 50, thus preventing the downhole throttling device 100 from continuing to move. When the spring piece 151 contracts under external force, it can disengage from the groove.

[0029] In this invention, the positioning cylinder 50 is connected to the downhole pipeline in series, so that the operator can control the depth of the positioning cylinder 50 into the well bottom by controlling the position of the positioning cylinder 50 connected to the downhole pipeline, thereby freely controlling the depth of the downhole throttling device 100 into the well bottom according to the actual needs of the site.

[0030] Furthermore, the spring 151 and the groove can be constructed into mutually compatible irregular shapes, thereby preventing the downhole throttling device 100 from prematurely ejecting when it moves to other gaps in the downhole pipeline (such as the connection between two adjacent casings) during the well entry process, which would affect the normal movement of the downhole throttling device 100 at the bottom of the well.

[0031] like Figure 1 As shown, in this invention, the ball seat 32 is connected to the outer cylinder 10 by a first shear pin 321, so that when the first shear pin 321 is sheared, the ball seat 32 can move relative to the outer cylinder.

[0032] Simultaneously, a pusher 60 is also provided on the ball seat. The pusher 60 is located on the side of the spring piece 151 away from the outer cylinder 10. Since the pusher 60 and the spring piece 151 are fixedly connected to the ball seat 32 and the outer cylinder 10 respectively, when relative movement occurs between the outer cylinder 10 and the ball seat 32, it can drive the spring piece 151 and the pusher 60 to move relative to each other, thereby pushing the spring piece 151 to open or retract. If necessary, a limiting ring 65 that can engage with the pusher 60 is also provided on the outer wall of the upper end of the spring piece 151. The limiting ring 65 can limit the stroke of the pusher 60 relative to the spring piece 151 moving upward in the axial direction, preventing the pusher 60 from disengaging from the spring piece 151.

[0033] The downhole throttling device 100 also includes a retrieval cylinder 70 connected to the upper end of the ball seat 32. The upper end of the retrieval cylinder 70 extends out of the ball seat 32, and a retrieval connector 75 is provided at the upper end of the retrieval cylinder 70. In this invention, the spring 151 is configured to push the spring 151 to retract when the pusher cylinder 60 moves upward relative to the spring 151, thereby causing the spring 151 to detach from the downhole casing.

[0034] Therefore, when it is necessary to retrieve the ball seat 32, simply lower the retrieval tool (not shown) into the gas well, connecting it to the retrieval connector 75. Then, lift the retrieval tool, thereby lifting the ball seat 32, making it retracted. During this process, the pusher 60 connected to the ball seat 32 also moves relative to the spring 151, causing the spring 151 to retract. This achieves the disengagement of the entire downhole throttling device 100 from the positioning cylinder 50.

[0035] like Figure 1 As shown, in a preferred embodiment, a sealing rubber sleeve 35 is also provided on the outer wall of the throttle nozzle 20. The lower end of the pusher 60 abuts against the sealing rubber sleeve 35, so that when the pusher moves downward relative to the spring 151, it can push the sealing rubber sleeve 35 to expand. Thus, when the spring 151 springs open and the downhole throttling device 100 is fixed to the positioning cylinder 50, by continuing to pressurize and push the ball seat 32 to continue to move downward relative to the outer cylinder 10, the pusher 60 moves downward relative to the throttle nozzle 20. At this time, the pusher 60 will push the rubber sleeve 35 to expand, thereby sealing the annular space radially between the outer cylinder 10 and the positioning cylinder 50, thereby enhancing the airtightness of the entire downhole throttling device 100 and ensuring that the downhole fluid can flow smoothly through the throttle nozzle 20.

[0036] Figure 2 for Figure 1 A partially enlarged view of the downhole throttling device 100 shown. (See attached image.) Figure 2As shown, a ratchet ring 16 is further provided on the outer wall of the outer cylinder 10, and a one-way tooth 18 that can engage with the ratchet ring is provided on the inner wall of the push cylinder 60. The outer cylinder 10 and the push cylinder 60 are connected by the ratchet ring 16. The ratchet ring 16 and the one-way tooth 18 on the push cylinder 60 engage with each other, so that the push cylinder 60 can only move downward relative to the outer cylinder 10. This arrangement prevents the push cylinder 60 from retracting upward relative to the outer cylinder 10 during the operation of the downhole throttling device 100, which would cause the rubber sleeve 35 to shrink prematurely and the seal to fail.

[0037] Furthermore, the ratchet ring 16 is connected to the outer cylinder 10 via a second shear pin 19. Thus, when the downhole throttling device 100 needs to be retrieved, the ball seat 32 can be lifted to create a shearing force between the pusher 60, which is fixedly connected to the ball seat 32, and the outer cylinder 10, until the shearing force cuts the second shear pin 19, allowing free movement between the ratchet ring 16 and the outer cylinder 10, and consequently, free movement between the outer cylinder 10 and the pusher 60. This prevents the one-way connection between the ratchet ring 16 and the one-way teeth 18 from hindering the pusher 60 from pushing the spring 151 to retract normally during the retrieval process.

[0038] Meanwhile, the second shear pin 19 is configured to have a shearing force greater than that of the first shear pin 321. This prevents the second shear pin 19 from being prematurely sheared during the compression of the rubber sleeve 32 by the pusher 60, which could lead to seal failure.

[0039] In addition, such as Figure 1 As shown, in a preferred embodiment, a sand shield 80 is also provided at the lower end of the throttle nozzle 20. The sand shield 80 can prevent various impurities in the formation from entering the throttle nozzle 20, thereby preventing the throttle nozzle 20 from being blocked, losing its throttling effect, and ultimately causing the downhole throttling device 100 to fail.

[0040] The working process of the downhole throttling device 100 according to the present invention is briefly described below.

[0041] When a gas well needs to be throttled, the downhole throttle device 100 of the present invention is first installed in the downhole pipe, so that the sealing ball 36 sets the ball seat 32. Then, high-pressure fluid is introduced into the downhole pipe, so that the downhole throttle device 100 reaches the positioning cylinder 50 under the push of the fluid, and then the spring piece 151 will automatically spring open and form a fixed connection with the positioning cylinder 50.

[0042] At this point, high-pressure fluid continues to be pumped into the well until the first shear pin 321 is sheared. Subsequently, the ball seat 32 will move downward relative to the outer cylinder 10, causing the pusher 60 to move downward relative to the outer cylinder 10. During this process, the pusher 60 will compress the rubber sleeve 35, sealing the annular space radially between the outer cylinder 10 and the positioning cylinder 50.

[0043] After the rubber sleeve 35 has fully expanded and sealed, acidic or alkaline liquid can be injected into the well. At this time, the sealing ball 36 will dissolve under the flushing effect of the liquid, allowing the first channel 12 to remain unobstructed. The downhole fluid can then pass smoothly through the throttle nozzle 20, thereby achieving throttling operations.

[0044] When it is necessary to retrieve the downhole throttling device 100, the retrieval tool is first lowered into the well and connected to the retrieval connector 75. The retrieval tool is then pulled up until the second shear pin 19 is sheared off.

[0045] After the second shear pin 19 is sheared, the ball seat 32 can move upward relative to the outer cylinder 10, driving the pusher 60 to move upward relative to the spring piece 151 until the pusher 60 abuts against the limiting ring 65. At this time, the pusher 60 pushes the spring piece 151 to retract, and the spring piece 151 disengages from the positioning cylinder 50.

[0046] When the pusher 60 comes into contact with the limiting ring 65, the ball seat 32 continues to be lifted. At this time, the pusher 60 connected to the ball seat 32 will push the spring 151 to move upward, thereby driving the outer cylinder 10 and the throttle nozzle 20, which are fixedly connected to the spring 151, to move upward until the entire downhole throttle device 100 is pulled out of the wellhead.

[0047] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A downhole throttling device, characterized in that, include: An outer cylinder (10) is disposed within the downhole casing, the outer cylinder having a first fluid flow channel (12), a sealing mechanism (30) inserted into the outer cylinder from its upper end, and a throttle nozzle (20) connected to the lower end of the outer cylinder. The sealing mechanism has a first state of sealing the outer cylinder and a second state of keeping the outer cylinder unobstructed. When the sealing mechanism is in the first state, the outer cylinder can move axially along the downhole casing under the action of high-pressure fluid from the first end; when the sealing mechanism is in the second state, fluid from the first end of the outer cylinder can flow out through the throttle nozzle. The sealing mechanism includes a ball seat (32) disposed within the outer cylinder and a sealing ball (36) capable of setting the ball seat. The sealing ball is made of a material that can dissolve under the influence of downhole fluid. The downhole throttling device also includes a positioning cylinder (50) connected to the downhole pipe body. The outer cylinder can extend into the positioning cylinder and move within it. A fixing member (15) is provided on the outer wall of the outer cylinder, and a connecting part (55) is provided on the inner wall of the positioning cylinder. The fixing member has a fixed state that can be connected to the connecting part and a free state that can be detached from the connecting part. The connecting part is configured as a groove inside the positioning cylinder, and the fixing member is configured as a spring piece (151) connected to the outer wall of the outer cylinder. The spring piece can open or retract radially along the positioning cylinder, thereby extending into or retracting from the groove. The ball seat is connected to the outer cylinder by a first shear pin (321), so that the ball seat can move relative to the outer cylinder. A pusher (60) is also provided on the ball seat. The pusher is located on the side of the spring piece away from the outer cylinder, so that when the pusher moves upward relative to the spring piece, it can push the spring piece to retract.

2. The downhole throttling device according to claim 1, characterized in that, It also includes a retrieval tube (70) connected to the upper end of the ball seat.

3. The downhole throttling device according to claim 2, characterized in that, A sealing rubber sleeve (35) is also provided on the outer wall of the throttle nozzle. The lower end of the pusher abuts against the sealing rubber tube, so that when the pusher moves downward relative to the spring, it can push the sealing rubber tube to expand.

4. The downhole throttling device according to claim 3, characterized in that, A ratchet ring (16) is provided on the outer wall of the outer cylinder, and a one-way tooth (18) is provided on the push cylinder that can engage with the ratchet ring.

5. The downhole throttling device according to claim 4, wherein the ratchet ring is connected to the outer cylinder by a second shear pin (19), the second shear pin being configured to have a shearing force greater than that of the first shear pin.

6. The downhole throttling device according to any one of claims 1 to 5, characterized in that, A sand guard (80) is also provided at the lower end of the throttle nozzle.

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